Ferrite antenna

ABSTRACT

The invention relates to a ferrite antenna, comprising at least one winding ( 4 ), which is arranged around a core ( 2 ) consisting of ferrite material. A second core ( 3 ), consisting of ferrite material and running coaxially to the first core ( 2 ), is allocated to the first core ( 2 ), which carries the winding ( 4 ) and is rigidly fixed in the coil carrier ( 1 ). Said second core, which can be displaced in an axial direction in the same coil carrier ( 1 ), is positioned in such a way that the opposing front faces of the two cores are placed at a predetermined distance from one another. Said distance can be altered by displacing the second core ( 3 ) in an axial direction in order to tune the antenna After tuning, the second core ( 3 ) can be fixed in or on the coil carrier ( 1 ).

[0001] The invention relates to a ferrite antenna, with at least onewinding which is wound about a core made of ferrite material, as well asa process for producing and tuning such a ferrite antenna.

[0002] The invention further relates to a key-less activation and/orclosure device for vehicles comprising an antenna which is arranged inthe door grip and which includes a core of ferrite material with atleast one winding.

[0003] It is known, in connection with inductive assembly componentsand, especially, inductive coils, to wind one or several windingsdirectly onto a core formed of ferrite material. Such inductive assemblycomponents are described, for example, in German Utility Design PatentNos. 298 04 135.9 and 298 24 118.8. With respect to thesethus-configured assembly components, a subsequent tuning to a desiredfrequency or inductive value is difficult and time-consuming.

[0004] For this reason, in connection with ferrite antennas, the windingis generally disposed on a coil carrier comprised of synthetic orplastic material and, for tuning to a desired frequency or inductivevalue, a ferrite core is inserted or threaded into the coil carrierwhich is itself, for example, conduit-shaped, the ferrite core beingmovable in the axial direction and being fixedly securable to the coilcarrier after the tuning, via, for example, adhesive securement. Aferrite antenna of this type is described, for example, in GermanUtility Design Patent No. 200 00 874.9.

[0005] With respect to such ferrite antennas, however, it is difficultto configure such antennas with greater than a predetermined length orwith less than a predetermined thickness. These limitations arise fromthe fact that the production of very small ferrite cores of large lengthis time-consuming and difficult and the fact that the thickness of thecoil carrier must be taken into account when considering the totalthickness of the building components.

[0006] In current day technology, and, especially, in the constructionof motor vehicles, there is increasing demand for inductive assemblycomponents and, especially, ferrite antennas, which ferrite antennas,due to installation reasons, should be as long and small as possible,whereby the ferrite antennas should nonetheless be tunable. Such ferriteantennas find use especially in connection with key-less actuationand/or closure devices for vehicles, whereby the ferrite antennas aredisposed in door grips, in the interior, or in the bumper.

[0007] The invention provides a solution to the challenge of creating aferrite antenna which is tunable but which can be, however, nonethelessconfigured as long and small. The production cost should be the lowestpossible achievable cost.

[0008] The solution to this challenge results in an apparatusconfiguration having, in accordance with the present invention, thefeatures set forth in the characterizing clause of the patent claim 1.Advantageous further configurations of the building components aredescribed in the dependent claims.

[0009] A key-less actuation and/or closure device for motor vehicleswith an antenna, which is disposed in the door grip and comprises a coreof ferrite material with at least one winding, is characterized inpatent claim 11.

[0010] A process for the production and for the tuning of an inductiveassembly component of this type is the subject matter of patent claim12. An advantageous further configuration of the process is described inclaim 13.

[0011] The core concept of the invention resides in providing thepossibility of the tuning of a second rod. Both ferrite cores aredisposed coaxial to one another in a coil carrier, whereby the firstferrite core, which supports a winding, is ab initio fixedly secured inthe coil carrier and the second ferrite core for tuning of the coil isdisposed in an axially displaceable manner in the coil carrier and isfirst fixedly secured in the coil carrier following the tuning. In thisconnection, the winding or, respectively, the windings, of the firstferrite core are directly wound about the core and it is also possiblethat the second core carries at least one winding.

[0012] Both ferrite cores can be comprised of the same form and axiallength, which leads to a sharp reduction of the overall production costsof the assembly components; they can, however, for special purposes,also be comprised of different forms and lengths. Ferrite cores withright-angled or round cross sections can be deployed and the coilcarriers are then configured to correspondingly accommodate therespective core form. The second ferrite core is, in connection with aright-angled cross sectioned configuration thereof, displaceablydisposed in the coil carrier while, in connection with a second ferritecore with a round cross section, the ability to displace such a ferritecore as well as the ability to threadably secure such a ferrite core canbe provided. For the installation of ferrite antennas in a door grip ofa vehicle as part of a key-less actuation and/or closure device, it canbe useful if the second ferrite core is pivotable relative to thelongitudinal axis of the first ferrite core through an acute angle whichis selected with respect to the respective design of the door grip up toa maximum angular value of 30°.

[0013] The fixed securement of the ferrite core in the coil carrier canfollow in a conventional manner via adhesive securement thereof. Anembodiment of a ferrite antenna in accordance with the invention isdescribed in closer detail hereinafter with reference to the attacheddrawings.

[0014] The drawings show

[0015]FIG. 1 is a side view of a ferrite antenna;

[0016]FIG. 2 is a plan view of the ferrite antenna shown in FIG. 1.

[0017] The ferrite antenna shown in FIGS. 1 and 2 comprises a coilcarrier 1 formed of synthetic or plastic material which is configured asa flat right-angled strip, the strip being provided, on its narrowdimension extent, with a securement tab 1.3 and, on its longitudinaledges, with two securement elements 1.1 and 1.2 each having a hookshaped cross section, the securement elements being spaced from oneanother in the longitudinal direction and each being specificallyconfigured for receiving a respective one of the two ferrite cores 2 and3. The ferrite cores 2 and 3 each comprise a right-angled cross sectionand are disposed with their broad dimension extents on or in the coilcarrier 1 such that the securement elements 1.1 and 1.2 extend over therespective narrow dimension extents of the ferrite cores.

[0018] A coil winding 4 is fixedly secured on the first ferrite core 2via direct winding thereonto, whereby the winding ends 4.1 are extendedout in the axial direction. The first ferrite core 2 is, directly afterits installation in the coil carrier 1, fixedly secured thereto via, forexample, adhesive securement.

[0019] The second ferrite core 3 is initially disposed on the coilcarrier 1 and in the securement element 1.2 in a manner which permitsaxial displacement of the ferrite core. To effect tuning of the assemblycomponents to a predetermined inductive value or frequency, the secondferrite core 3 is displaced relative to the first ferrite core 2 in theaxial direction (arrow A) until the front sides of both ferrite cores 2and 3, which face one another, are disposed at precisely the desiredspacing from one another. Then, the second ferrite core 3 is, as well,fixedly secured to the coil carrier via, for example, adhesivesecurement.

[0020] In order to facilitate the installation of the illustratedferrite antenna in the door grip of a motor vehicle, as can be deducedby reference to FIG. 2, the second ferrite core 3 is swung relative tothe longitudinal axis of the first ferrite core 2 through an acute angleα which, in the illustrated embodiment, amounts to only a few degreesbut which can, however, depending upon the respective design of the doorgrip, amount to a maximum of 30°.

[0021] The production and the tuning of the ferrite antennas can beperformed, for example, in accordance with the following process steps:

[0022] a) positioning the coil carrier 1 in readiness;

[0023] b) positioning the two ferrite cores 2 and 3;

[0024] c) winding of the first ferrite core 2 with a winding 4;

[0025] d) disposing the first ferrite core 2 in the coil carrier 1 andfixedly securing the first ferrite core 2 in the coil carrier 1;

[0026] e) disposing the second ferrite core 3 in the coil carrier 1;

[0027] f) tuning the assembly components via axial displacement of thesecond ferrite core 3 in the coil carrier 1;

[0028] g) fixedly securing the second ferrite core 3 in the coil carrier1 via adhesive securement.

1. A ferrite antenna with at least one winding which is wound about acore formed of ferrite material, characterized in that disposed relativeto the first ferrite core (2), which supports the winding (4) or,respectively, the windings, and which is fixedly disposed in a coilcarrier (1), is a second ferrite core (3) of ferrite material, thesecond ferrite core being coaxial to the first ferrite core (2) andbeing moveable in an axial direction within the same coil carrier (1)such that the spacing between the facing front surfaces of both ferritecores (2, 3), which can be varied by movement of the second ferrite core(3) in the axial direction for tuning purposes, is set at apredetermined spacing, whereby the second ferrite core (3) is, followingthe tuning process, fixedly securable in or on the coil carrier (1). 2.A ferrite antenna according to claim 1, characterized in that thewinding (4) or, respectively, the windings, are directly wound onto thefirst ferrite core (2).
 3. A ferrite antenna according to claim 1 or 2,characterized in that the second ferrite core also supports at least onewinding.
 4. A ferrite antenna according to one of the claims 1-3,characterized in that the second ferrite core (3) is comprised of thesame form and axial length as the first ferrite core (2).
 5. A ferriteantenna according to one of the claims 1-4, characterized in that bothferrite cores (2, 3) comprise a right-angled cross section.
 6. A ferriteantenna according to claim 5, characterized in that the coil carrier (1)is comprised of synthetic or plastic material and is configured as aflat strip on which the broad dimension extent of each ferrite core (2,3) is disposed and which comprises, on at least one of its longitudinaledges, at least one securement element (1.1, 1.2) having a hook shapedcross section and configured for extending over the narrow dimensionextent of a respective one of the two ferrite cores.
 7. A ferriteantenna according to one of the claims 1-4, characterized in that bothferrite cores comprise a round cross section.
 8. A ferrite antennaaccording to claim 7, characterized in that the coil carrier iscomprised of synthetic or plastic material and is configured as aconduit or a partial conduit which encircles at least a portion of theperiphery of the respective core.
 9. A ferrite antenna according to oneof the claims 1-8, characterized in that the ferrite cores (2, 3) arefixedly secured in or on the coil carrier (1) via adhesive securement.10. A ferrite antenna according to one of the claims 1-9, characterizedin that the second ferrite core (3) is disposed in a pivotable mannerrelative to the longitudinal axis of the first ferrite core (2) forpivoting about an acute angle (a) up to a maximum of 30°.
 11. A key-lessactuation and/or closure device for motor vehicles with an antenna,which is disposed in the door grip and comprises a core of ferritematerial with at least one winding, characterized in that disposedrelative to the first ferrite core (2), which supports the winding (4)or, respectively, the windings, and which is fixedly disposed in a coilcarrier (1), is a second ferrite core (3) of ferrite material, thesecond ferrite core being coaxial to the first ferrite core (2) andbeing moveable in an axial direction within the same coil carrier (1)such that the spacing between the facing front surfaces of both ferritecores (2, 3), which can be varied by movement of the second ferrite core(3) in the axial direction for tuning purposes, is set at apredetermined spacing, whereby the second ferrite core (3) is, followingthe tuning process, fixedly securable in or on the coil carrier (1). 12.A process for producing and tuning a ferrite antenna according to one ofthe claims 1-10, characterized by the following process steps: a)positioning the coil carrier in readiness; b) positioning the twoferrite cores; c) winding of the first ferrite core with a winding; d)disposing the first ferrite core in the coil carrier and fixedlysecuring the first ferrite core in the coil carrier; e) disposing thesecond ferrite core in the coil carrier; f) tuning the assemblycomponents via axial displacement of the second ferrite core in the coilcarrier; g) fixedly securing the second ferrite core in the coil carriervia adhesive securement.
 13. A process according to claim 12,characterized in that the fixed securement of the first ferrite core andthe second ferrite core in the coil carrier is effected via adhesivesecurement.